Scope Planning

Functional requirements describe the characteristics of the final deliverable in ordinary non-technical language. They should be understandable to the customers, and the customers should play a direct role in their development. Functional requirements are what you want the deliverable to do.

Vehicle Example

If you were buying vehicles for a business, your functional requirement might be: "The vehicles should be able to take up to a one ton load from a warehouse to a shop".

Computer System Example

For a computer system you may define what the system is to do: "The system should store all details of a customer's order".

The important point to note is that what is wanted is specified and not how it will be delivered.